(1) Field of the Invention
The invention relates to a storage battery cover, and more particularly to a storage battery cover offering added protection against leakage when a battery using the cover of the invention is tipped to any one of its sides or inverted.
(2) Description of the Prior Art
Conventional storage batteries include a battery housing having a housing and a cover for closing an open top end of the casing. The battery housing is a rectangular casing having multiple compartments or cells for receiving cell plates and electrolyte therein. The cover device is heat sealed to an open top end of the battery housing casing.
The cover device often includes a main cover part and a sub-cover part. The main cover part has a horizontally disposed plate body with a top face formed by a rectangular confining wall. The confining wall is divided by multiple partitions and associated chambers. The main cover further includes multiple service ports for pouring electrolyte into respective cell compartments within the casing and multiple degassing vents and drain-back return holes associated with each cell.
The sub-cover is integrally secured to the main cover after electrolyte has been poured into the cell compartments through the service ports. The sub-cover part is heat sealed to the main cover part along its perimeter and at top edges of the partitions and chamber walls. The chambers and partitions ultimately form enclosed chambers and associated paths from the cell vent and return hole of each cell to multiple atmospheric vents. The chambers typically include relatively large containment areas for holding electrolyte spilled into the battery cover when the battery is tipped.
In operation, heat that is generated during electrolysis causes the electrolyte and water in the electrolyte to evaporate. This evaporation is referred to as xe2x80x9cgassingxe2x80x9d. Gassing of the cells occurs at any point the battery reaches the hydrogen over-voltage, producing bubbles that break at the surface introducing a mist into the venting gas stream. In conventional batteries, the vaporized electrolyte was released to atmosphere through an atmospheric vent in the cover device. Loss of electrolyte through the atmospheric vent requires replenishing electrolyte in the battery housing periodically. In order to overcome electrolyte loss, a battery housing with a cover capable of recovering the vaporized electrolyte was developed, thereby obviating the need for replenishing the electrolyte in the battery housing.
When the electrolyte in the cell compartments undergo electrolysis and evaporates due to the heat that is generated, the vaporized electrolyte flows into the path formed in the cover through the cell vents or drain-back holes. Since the interior of the cover is exposed to the atmosphere via the atmospheric vent, the interior temperature of the cover is less than that of the vaporized electrolyte entering the cover. Thus, heat transfer occurs so that the vaporized electrolyte condenses, and the resulting condensate flows back into the corresponding cell compartments via the drain-back holes. The paths are often sloped towards the drain-back holes to further facilitate the return of electrolyte to the respective cells. Since the vaporized electrolyte is recovered instead of released to atmosphere, there is no need to periodically replenish the electrolyte in the battery housing.
Although these batteries prevent electrolyte loss during normal operation, the battery will leak, and in many cases pour, electrolyte from the atmospheric vents when the battery is tipped to one side, inverted or agitated. Batteries are often placed in a non-upright position during shipping, handling or accidents, such as car wrecks. A significant threat to person and property arises when electrolyte leaks from a battery.
Various approaches have been taken in the past to deal with the problem of electrolyte spilling or leaking from a battery when it is tipped to any one of its sides. Many of the arrangements are acceptable in situations where the battery is tilted to its side and not subjected to vibration or other forms of movement. However, the related art has yet provided a cost effective battery cover providing total steady state leak protection when the battery is tipped to one side and substantial resistance to electrolyte leakage when subjected to vibration, agitation or inversion.
U.S. Pat. No. 1,605,820 to Edwards discloses a multilevel chamber configuration for each cell. The chamber includes two opposed inclined partitions for preventing electrolyte spills when the battery is tipped to one side. The chamber configuration provides no inverted leak protection. Furthermore, the large chamber configuration provides very limited protection against vibration or agitation when tipped to one side.
U.S. Pat. No. 3,597,280 to Hennen disclosed a multiple vent plug assembly for merely reducing spillage when a battery is partially tipped or completely inverted. The plug assembly incorporates a multi-chamber configuration designed to contain a substantial portion of electrolyte prior to spilling the electrolyte to atmosphere. The Hennen patent does not disclose a chamberless cover design or provide substantial leak protection over extended periods of time.
U.S. Pat. No. 4,348,466 to Elehew et al. discloses a large rectangular chamber configuration having an inlet in communication with a respective cell. Each chamber has an outlet off to one side of and below the inlet. A passage associated with the chamber outlet is provided for containing and holding electrolyte. The passage has an outlet in communication with an atmospheric vent. The arrangement is such that the chambers and associated passages are of sufficient volume to retain the amount of electrolyte displaced into them when equilibrium is achieved between levels of electrolyte in the cells and respective chambers and passages.
The Elehew et al. patent requires that a portion of the passage be above the chamber inlet regardless to which side the battery is tipped. When the chambers and the passages fill with electrolyte, an airlock is developed which prevents additional flow of electrolyte from the cell into the chamber and passage configuration.
The Elehew et al. patent provides no leak protection when the battery is inverted and provides only steady state protection when the battery is tipped to one side. As seen from viewing the chamber and passage configuration of the Elehew et al. patent, when a battery using the Elehew et al. cover is tipped on various sides and vibrated or agitated, it is very likely that electrolyte will spill out of the chamber and run into the passage to the venting area. The large chambers and passage configuration in Elehew et al. allows substantial amounts of electrolyte to spill into the battery cover; thus, increasing the likelihood of electrolyte being spilled into the venting area and ultimately leaking outside the battery systems. The Elehew et al. patent is directed towards preventing leak protection at a steady-state equilibrium when the battery is tipped to one side. Having substantial amounts of electrolyte in the cover and limited flow restriction substantially increases the likelihood that electrolyte will spill if the battery is vibrated or agitated after arriving at an equilibrium in a non-upright position.
Similar configurations are shown in U.S. Pat. No. 5,380,604 to Hampe et al. and U.S. Pat. No. 5,424,146 to Lin. Both patents disclosed leak resistant battery covers having chambers associated with each cell. The chambers have guides for controlling the flow of acid. However, each cover is designed to allow a significant amount of electrolyte to flow into the respective cover and provides no protection against electrolyte leakage when the battery is inverted and very limited protection when vibrated or agitated.
The German Patent No. 4,216,563 discloses a dual section cover having a chamber associated with each cell. Each chamber is sized so that when the battery is tipped or inverted, no more acid from a respective cell enters the gas collection chamber than the chamber can contain. Although the German patent attempts to address inverted leak protection, allowing such substantial amounts of electrolyte to flow out of the cells and into the cover substantially increase the risk of electrolyte leaking outside of the battery system.
Aside from the above arrangements, far more complex arrangements are known which are used on aircraft batteries and the like which not only deal with the problem of electrolyte flowing from the cell when tipped to any one of its sides, but also maintains the battery in operation when completely inverted. These designs are not cost effective for the majority of battery applications. Accordingly, there remains a need to provide an anti-spill battery cover for liquid electrolyte batteries which is relatively inexpensive to manufacture, prevents spillage of electrolyte when tipped toward or onto any one of its sides, provides additional resistance to spillage when vibrated or agitated while tipped toward or on any one of its sides, and prevents spillage of electrolyte when the battery is substantially or completely inverted. Furthermore, there is a need for a chamberless battery cover of limited volume capable of forming an air-lock in a short period of time after tipped or inverted in order to minimize the amount of electrolyte entering the cover and significantly reducing the potential of electrolyte reaching an atmospheric vent. A need exists for a chamberless, leak resistant battery cover using only one atmospheric vent in order to further reduce the likelihood of electrolyte spills. A need remains for a battery cover having the above features in order to prevent harm to person and property caused by contact with electrolyte or from the potential of fire and explosion if exhaust gases are ignited.
The present invention is directed to a leak resistant battery cover for storage batteries. The battery cover provides a labyrinth of passages providing a path from each cell vent to the atmospheric vent. The labyrinth is configured to provide a portion of each path above a level in which the electrolyte in the respective cells attains when the battery is tipped on any one of its sides or rotated ninety (90) degrees from an upright position. The labyrinth configuration prevents electrolyte from reaching the atmospheric vent and spilling out of the battery.
The passages of the labyrinth may include portions extending horizontally from a passage wall towards the center of the passage. These horizontally extending passages are generally perpendicular to the passage wall or angled in a manner obstructing the flow of electrolyte toward the atmospheric vent. Preferably, the horizontally extending passages alternate from opposing sides of the passage. The labyrinth configuration of the current invention provides improved leak protection over the above discussed prior art when the battery is tipped to one side. Additionally, the substantially convoluted passages provide inverted leak resistance.
The convoluted passages in conjunction with the partitions operate to form an air-lock between the cell vent and the atmospheric vent. By proving such a convoluted path for air to travel, an air-lock is formed in the passages. When air is prevented from entering the battery, additional electrolyte is prevented from leaving each cell, entering the labyrinth and ultimately leaking through the atmospheric vent.
The passages of the labyrinth may also include portions extending vertically from a passage floor or ceiling. The vertically extending passages provide enhanced leak protection when the battery is inverted. Preferably, the vertically extending partitions alternate from the floor and ceiling and the portions extending from the ceiling are substantially longer than the partitions extending from the floor in order to provide a greater electrolyte barrier when inverted. The vertically extending partitions aid in forming an air-lock and preventing air from entering the cells.
Accordingly, one aspect of the current invention is to provide a leak resistant battery cover for a lead acid battery of the type including a housing having a plurality of cells containing electrolyte and a plurality of partition walls separating the cells. The cover includes (1) a cover having a floor and ceiling forming an interior area therebetween, wherein the cover includes a bottom adjacent, the battery housing wherein the cover sealably engages in the housing and partition walls; (2) a plurality of cell vents in and extending through the bottom of the cover wherein each cell vent is adapted to communicate gases within the corresponding cells of the battery to the interior area of the cover; (3) an atmospheric vent on the cover adapted to communicate gases from within the interior area of the cover to atmosphere; (4) a labyrinth system between said floor and ceiling in the interior area of the cover form a plurality of narrow passages wherein the passages formed of a plurality of convoluted paths communicating each cell vent to the atmospheric vent and each cell vent communicates substantially immediately with one of the passage of the labyrinth; and (5) a plurality of cell drains on said floor and extending through the bottom of the cover wherein the cell drains communicate with the passages, and the cell drains are adapted to communicate liquid in the passages to respective cells. The passages of the labyrinth are so arranged that each of said paths has a branch above an electrolyte level for the corresponding cell when the battery is rotated as much as ninety degrees from an upright position.
Another aspect of the current invention is to provide a labyrinth adapted to provide for two or more of the passages communicating with each cell vent to converge into a common passage in the labyrinth prior to the atmospheric vent, wherein the path from each cell vent to the atmospheric vent is common for respective cells. Furthermore, all of the passages communicating with each cell vent may converge into a final common passage in the labyrinth prior to the atmospheric vent.
Still another aspect of the current invention is to provide a labyrinth having passages sloped towards the cell drains to allow liquid electrolyte in the passages to flow into respective cells. Additionally, the cell vent and the cell drain are an integrated vent and drain back unit.
Another aspect of the current invention is to provide a labyrinth of passages which are substantially convoluted and substantially or entirely encircle each respective cell vent. Preferably, each path to atmosphere for each cell has a branch running substantially near a portion of the periphery of the cover.
Still another aspect of the current invention is to provide a labyrinth wherein each path formed by the passages form one path to atmosphere for each cell. Various portions of each path may be common to another path. Additionally, the passages of the labyrinth may be adapted to provide a path from each cell vent to the atmospheric vent which crosses the lateral axis twice.
Another aspect of the current invention is to provide a battery cover having a transverse axis perpendicular to the lateral axis with passages adapted to provide a path from each cell vent to the atmospheric vent having a portion substantially along the transverse axis. Furthermore, the battery may have each cell vent, each cell drain and the atmospheric vent on one side of the lateral axis. Generally, the battery cover is adapted for a six cell lead acid battery wherein the battery cover includes six cell vents, six cell drains and one atmospheric vent. Preferably, the battery cover is constructed of a lower cover portion and an upper cover portion. The lower and upper cover portions sealably engage one another to form the labyrinth system.
Another aspect of the current invention is to provide a cover including a second atmospheric vent wherein approximately half of the cell vents communicate with each atmospheric vent.
Yet another aspect of the current invention is to provide the passages of the labyrinth with a plurality of horizontally extending partitions extending into the passages to provide resistance to any flow of liquid, towards the atmospheric vent when the battery is toppled. The horizontally extending partitions extend from interior sides of the passages of the labyrinth and are often slanted against a direction of flow of electrolyte toward the atmospheric vent to provide further resistance against the flow of liquid electrolyte towards the atmospheric vent when the battery is toppled. Preferably, the horizontally extending partitions alternate from opposing interior sides of the passages of the labyrinth.
Still another aspect of the current invention is to provide the passages of the labyrinth with a plurality of vertically extending partitions extending into the passages to provide resistance to the flow of liquid towards the atmospheric vent. The vertically extending partitions aid in restricting electrolyte flow in the passages and in providing an airlock between the cells and the atmospheric vent when the battery is inverted. The vertically extending partitions may extend from either an upper or lower portion of the passages. Preferably, the upper and lower vertically extending partitions alternate along the passage. The vertically extending partitions extending from the upper portion of the passage extend below a level in which the vertically extending partitions extending from the lower portion extend. The vertically extending partitions provide an obstructed path along the passage.
Yet another aspect of the current invention is to provide the common passage of the labyrinth with a plurality of substantially vertically extending partitions adapted to provide resistance to the flow of liquid towards the atmospheric vent. The vertically extending partitions extend from an upper and lower portion of the common passage and alternate along the common passage. The vertically extending partitions extending from the upper portion of the common passage extend below a level in which the vertically extending partitions extending from the lower portion extend. The partitions provide an obstructed path to the atmospheric vent. The vertically extending partitions extending from the upper and lower portions of the common passage are preferably substantially adjacent along the common passage.
Still another aspect of the current invention is to provide the common passage of the labyrinth with an entrance, wherein the entrance includes a vertically extending partition adapted to provide resistance to the flow of liquid towards the atmospheric vent. The vertically extending partition at the entrance further aids in providing an airlock between the cells and the atmospheric vent when the battery is inverted.
Another aspect of the current invention is to provide a leak resistant battery cover for a lead acid battery of the type including a housing having a plurality of cells containing electrolyte and a plurality of partition walls separating the cells, the cover includes: (1) a cover having floor and ceiling forming an interior area therebetween, wherein the cover includes a bottom adjacent the battery housing wherein the cover sealably engages the housing and partition walls; (2) a plurality of cell vents in and extending through the bottom of the cover wherein each cell vent is adapted to communicate gases within the corresponding cells of the battery to the interior area of the cover; (3) an atmospheric vent on the cover adapted to communicate gases from within the interior area of the cover to atmosphere; (4) a labyrinth system between said floor and ceiling in the interior area of the cover form a plurality of narrow passages wherein the passages form a plurality of substantially convoluted paths to communicate each cell vent to the atmospheric vent wherein each cell vent communicates substantially immediately with one passage of the labyrinth; and (5) a plurality of cell drains on said floor and extending through the bottom of the cover wherein the cell drains communicate with the passages wherein the cell drains are adapted to communicate liquid in the passages to respective cells, and the passages of the labyrinth are so arranged that each of said paths has a branch above an electrolyte level for the corresponding cell when the battery is rotated as much as ninety degrees from an upright position, wherein the labyrinth is adapted to provide for two or more of the passages communicating with each cell vent to converge into a common passage in the labyrinth prior to the atmospheric vent wherein the path from each cell vent to the atmospheric vent has a portion in common with one or more other said paths.